An air ejection device for a frictional-resistance reducing ship has been known, which is formed by arranging a plurality of air ejection units in a ship width direction on an outer plate of a ship's bottom (see, for example, Patent Document 1). In this air ejection device for the frictional-resistance reducing ship, the air ejection units are arranged in a staggered manner in the ship width direction, by which an enhancement of strength of a ship body is achieved.
In addition, a ship-body frictional resistance reducing device is described in Patent Document 2, in which a plurality of air ejection holes are formed on an outer plate portion of a ship's bottom. In this ship-body frictional resistance reducing device, an air chamber formed inside a ship in the ship width direction on a bottom of a bow of the ship is provided, and a pair of air-bubble generating side air chambers is provided at left and right sides slightly behind the air chamber. Each of the air chambers is divided into a plurality of sub-chambers, and the air ejection holes are formed on the outer plate portion of the ship's bottom corresponding to each of the sub-chambers.    Patent Document 1: Japanese Patent Application Laid-open No. H11-227675    Patent Document 1: Japanese Patent Application Laid-open No. 2008-114710